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200 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 4
Hydractinia prolifica, new species
Plate 22, Fig. 1
Trophosome.—Colony covers closely a large gastropod shell. Nutritive zooids are placed close together around the margin, but they are
pretty well crowded out of the portion of the shell farthest from the
margin. The individual zooids have great power of extension even for
Hydractinia, the longest observed being 4 mm. The tentacles are fewer
than usual, 12-15.
Spines.—The spines are long, up to 0.75 mm, and very numerous;
usually smooth, but sometimes rough or even spiny on the margin.
Gonosome.— (Only male colony observed.) The generative zooids
are crowded on the more protected portion of the shell; they are small,
about 1.0 mm in length, without tentacles. The gonophores are large for
the size of the hydrocaulus, scattered but relatively close together, as
many as 6 of them, on the one zooid.
Other Zooids.—No sensory or defensive zooids could be distinguished
in the preserved specimens.
Distribution.—Station 944-39, 10 miles SW of Secas Islands, Panama, 30 fathoms.
Remarks.—This species resembles H. echinata (Fleming) more than
any of the species so far reported from the Pacific coast, but the gonophores are more numerous, the spines longer, more slender, with less
tendency to form secondary spines, and much more numerous. If the
distribution range of H. echinata were more propitious it might seem
possible that H. prolifica was derived from that species.
Family Pennaridae
Genus PENNARIA
Pennaria tiarella (Ayres)
Globiceps tiarella Ayres, Proc. Boston Soc. Nat. Hist., 1854, p. 193.
Pennaria tiarella McCrady, Gymno. Charleston Har., 1859, p. 153.
Fraser, Hancock Hyd., 1, 1938, p. 25.
Fraser, ibid., 3, 1938, p. 132.
Distribution.—San Pedro, Calif.; San Francisco Bay, east of Panama
City, shore; off La Libertad, Ecuador, 10 fathoms.

200 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 4
Hydractinia prolifica, new species
Plate 22, Fig. 1
Trophosome.—Colony covers closely a large gastropod shell. Nutritive zooids are placed close together around the margin, but they are
pretty well crowded out of the portion of the shell farthest from the
margin. The individual zooids have great power of extension even for
Hydractinia, the longest observed being 4 mm. The tentacles are fewer
than usual, 12-15.
Spines.—The spines are long, up to 0.75 mm, and very numerous;
usually smooth, but sometimes rough or even spiny on the margin.
Gonosome.— (Only male colony observed.) The generative zooids
are crowded on the more protected portion of the shell; they are small,
about 1.0 mm in length, without tentacles. The gonophores are large for
the size of the hydrocaulus, scattered but relatively close together, as
many as 6 of them, on the one zooid.
Other Zooids.—No sensory or defensive zooids could be distinguished
in the preserved specimens.
Distribution.—Station 944-39, 10 miles SW of Secas Islands, Panama, 30 fathoms.
Remarks.—This species resembles H. echinata (Fleming) more than
any of the species so far reported from the Pacific coast, but the gonophores are more numerous, the spines longer, more slender, with less
tendency to form secondary spines, and much more numerous. If the
distribution range of H. echinata were more propitious it might seem
possible that H. prolifica was derived from that species.
Family Pennaridae
Genus PENNARIA
Pennaria tiarella (Ayres)
Globiceps tiarella Ayres, Proc. Boston Soc. Nat. Hist., 1854, p. 193.
Pennaria tiarella McCrady, Gymno. Charleston Har., 1859, p. 153.
Fraser, Hancock Hyd., 1, 1938, p. 25.
Fraser, ibid., 3, 1938, p. 132.
Distribution.—San Pedro, Calif.; San Francisco Bay, east of Panama
City, shore; off La Libertad, Ecuador, 10 fathoms.